pxa3xx_nand: adjust timing of Micron NAND flash

Slow down the tRp of Micron NAND flash timing.
Signed-off-by: NHaojian Zhuang <haojian.zhuang@marvell.com>
Signed-off-by: NEric Miao <eric.y.miao@gmail.com>

drivers/mtd/nand/pxa3xx_nand.c

@@ -235,7 +235,7 @@ static struct pxa3xx_nand_timing micron_timing = {
 	.tWH	= 15,
 	.tWP	= 25,
 	.tRH	= 15,
-	.tRP	= 25,
+	.tRP	= 30,
 	.tR	= 25000,
 	.tWHR	= 60,
 	.tAR	= 10,